Informed consent, decisional capacity, autonomy, and withdrawal rights

The manuals converge on informed consent as a structured, documented process that happens before study specific procedures and is supported by clear oral and written explanation. Across the extracts, they repeatedly recommend time for questions, understandable language, confirmation of comprehension, and documentation with signed copies or source records. Many also treat consent as ongoing rather than a one time signature, with re consent or updated consent when new information emerges. They also strongly converge on voluntariness and withdrawal rights. The sources consistently state that participation is voluntary, that refusal or withdrawal should not bring penalty or loss of care, and that participants may decline optional elements such as recordings, saliva collection, support person contact, or later crossover sessions. Several manuals add explicit non coercion language and stress that consent can be invalidated by coercion or incapacity. Where they differ is in the level of consent detail and the kinds of safeguards emphasised. Some manuals focus on specific study features such as video or audio recording, media disclosure, rescue medication, support touch, or blinded dose identity, while others emphasise capacity screening, literacy, or exclusion of people unable to understand the materials. A smaller set also addresses investigator initiated withdrawal, safety based limits on leaving after dosing, or special handling for optional components and collateral contact, so the balance between autonomy and safety varies by protocol.